<template>
  <div class="son">son组件:{{ sonNum }}</div>
</template>
<script>
import { ref } from 'vue'
export default {
  setup () {
    const sonNum = ref('我是son')
    return { sonNum }
  }
}
</script>
<style>
.son {
  width: 300px;
  height: 300px;
  background-color: #f00;
}
</style>
